Apparatus for carrying out chemical reaction sequences

ABSTRACT

An apparatus for carrying out chemical reaction sequences includes a stack of reaction plates arranged one above another and displaceable according to choice step by step in relation to one another, which are provided with passages arranged at the stepping interval, one of which passes in each case is formed as reaction chamber. A plate displacement device serves for the displacement of the respective plate, according to choice, in relation to the remaining plate stack. A pressure application part of a clamping device is provided with a faculty for movement of the plates in relation to one another between a pressure application position with sealing clamping together of the plates and a release position. A force transmission device in the form of a two-armed lever couples the plate displacement device with the pressure application part, so that on a movement of the plate displacement device beyond one of the two outer plate displacement positions into an end position the pressure application part is moved into the pressure application position.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus for carrying out chemical reactionsequences, having

a stack of reaction plates arranged one above another and optionallydisplaceably in relation to one another step by step in a direction ofdisplacement perpendicular to the stacking direction, which plates areprovided with passages arranged at the stepping interval, one of whichin each case is formed as reaction chamber,

a plate displacement device for the optional displacement of therespective plate in relation to the remaining plate stack by means of aplate displacement part drivable according to choice, which is movablymounted on a head of the plate displacement device which is movableaccording to choice in the stack direction between pate displacementpositions allocated to the individual plates, and

a tightening device having a presser part acting on the plate stack,which presser part is movable between a pressure application positionwith sealing clamping together of the plates and a release position withpossibility of movement of the plates in relation to one another.

An apparatus of this kind is known (EP-A-164,206). With it it ispossible simultaneously to carry out a series of biochemical reactions,especially the synthesis of DNA fragments, as also known per se fromEP-A-181,491, using a stack of plates of circular disc form which can berotated manually in relation to one another. The bases A, C, G, T arefed to the stack by way of four passages. According to the desiredsequence the reaction chamber of the respective plate is brought intoalignment with the passage delivering the desired base. The apparatusknown from the initially mentioned EP-A-164,206 permits an automaticdisplacement (rotation) of the individual plates in relation to oneanother, so that a plurality, corresponding to the number of plates, ofsimultaneous synthesis reactions can be carried out with a high numberof reaction steps in computer-supported manner without manualintervention. However in this known solution the apparatus expense isconsiderable. In all four drive systems are necessary: a height drivewhich drives a drive spindle for the height adjustment of the platedisplacement device and a drive spindle for a shift lock a drive as partof the plate displacement device, which brings a plate displacement partin the form of a presser roller drivable according to choice by means ofa further drive into and out of engagement with the externalcircumference of the respective plate; a fourth drive in the form of alifting cylinder which serves for the movement of the presser part inthe form of a plate. This plate is arranged above the plate stack and ismovable between the release position, in which the plates are rotatablein relation to one another for the preparation of the next reaction, andthe pressure application position, in which the plates are pressedtogether in sealing manner by the pressure application part. Thereaction step in each case is carried out in the pressure applicationposition.

SUMMARY OF THE INVENTION

In contrast thereto the problem of the invention consists in preparingan apparatus of the initially stated kind, with simplified constructionand reliable function.

This problem is solved in that the clamping device comprises aforce-transmission device coupled with the presser part, on which devicethe plate displacement device acts for the movement of the presser partout of the release position into the pressure application position on amovement of the head of the plate displacement device beyond one of thetwo outer plate displacement positions into an end position.

Thus in accordance with the invention the pressure application part isactuated by the plate displacement device so that a separate drivesystem for the pressure application part can be eliminated.

An especially simple form of construction in accordance with theinvention is characterised in that the force-transmission devicecomprises a two-armed lever, one end of which co-operates with the platedisplacement device and the other end with the pressure applicationpart. Thus the two-armed lever transmits the upward movement of theplate displacement device, with sign reversal, to the pressureapplication part to be moved downwards.

For the precise adjustment of clamping pressure, for example afterchange of the number of reaction plates, it is proposed that at leastone of the ends of the two-armed lever is provided with a clampingpressure adjustment device. It is preferredly provided here that theclamping pressure adjustment device is formed by an adjustable doublewedge.

In the known apparatus as named at the outset a shift lock (in the formof the threaded spindle 63) movable in the stack direction with theplate displacement device is provided which blocks that plate directlyabove the plate approached by the plate displacement device in eachcase, in that this plate is pushed correspondingly far from above intomutually aligned passage bores of the plates. Each plate is providedwith a row of passage bores of this kind spaced from one anotheraccording to the step interval. It is disadvantageous in thisarrangement that the plate arranged beneath the plate to be displaced isnot fixed, so that an uncontrolled accompanying rotation cf this platecan occur. If this accompanying rotation is not corrected, then in thenext reaction a wrong reaction may possibly be executed in this plate.An only partial accompanying rotation of this plate would be still moreunfavourable, since then all passages through this plate might possiblybe blocked.

Alternatively or in addition to the above-described measures inaccordance with the invention, to increase the operational reliabilityof the apparatus of the kind as initially stated, with simpleconstruction, it is proposed that the shift lock also acts in blockingmanner upon the plate immediately below the plate approached by theplate displacement device.

To simplify the mechanical assembly, especially by the elimination ofthe spindle drive in the known apparatus, it is proposed that anengagement element cc-operating with counter-engagement elementsarranged on the plates is rigidly arranged on the head both above andbelow the plate displacement part.

In order, again in a constructionally simple manner, to ensure areliable fixing of the respective plates in all their possible positionsin displacement, it is proposed that one of the elements, engagementelement and counter-engagement element, comprises an engagementprojection, and that the other element comprises a plurality ofengagement grooves arranged side by side in the displacement directionat the step interval,extending parallel to the stacking direction andadapted in cross-section to the engagement projection.

Alternatively it can however also be provided that one of the elements,engagement element and counter-engagement element, comprises anengagement groove extending parallel with the stacking direction, andthat the other element comprises several engagement projections arrangedside by side in the displacement direction at the step interval andadapted to the groove cross-section.

In the case of formation of the apparatus according to the inventionwith a pressure application part arranged at the upper stack end it isproposed to form this with an engagement groove for the upper engagementprojection of the head.

According to a further embodiment of the invention it is proposed thatthe plate displacement part is formed by a displacement projectionmovable in the displacement direction, which projection co-operates withcounter-projections formed on the plates. It is especially preferredlyprovided in this case that the displacement projection, in anintermediate position of the plate displacement device betweensuccessive plate displacement positions, is freely movable throughbetween the counter-projections of successive plates. This has the greatadvantage that the drive 75 for the horizontal movement of the head intoand out of engagement with the plate stack, necessary in the knownapparatus, can be eliminated.

For the sake of simplicity it can be provided here that the displacementprojection and/or the counter projections are of pin form.

In normal operation with a moderate number of plates, for example 10plates, there is no need to fear that the one or the other plate willjam in displacement If nonetheless such jamming should occur, which canhappen especially in the case of a high number of plates, it is proposedthat the plate displacement apparatus is provided with an overloadsafety device.

Such an overload safety device, distinguished by simple structure andreliable function, is characterised according to the invention in thatthe plate displacement part of pin form is made electrically conductive,in that an initial stress spring, in a normal position of the platedisplacement part, presses the plate displacement part against aninsulating part, and in that on overloading the plate displacement partslides away from the insulating part and is pressed by the initialstress spring against an electrically conductive contact plate.

In order, even in the case of relatively slight clamping-togetherpressure, to ensure a reliable sealing of the passages in the transitionregion of successive plates, O-ring seals are proposed betweensuccessive plates.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained hereinafter by a preferred example ofembodiment with reference to the drawing, wherein :

FIG. 1 shows a simplified isometric overall view of the apparatusaccording to the invention;

FIG. 2 shows a lateral elevation of the arrangement in FIG. 1 (seen inthe direction II);

FIG. 3 shows a section along the line III--III in FIG. 2;

FIG. 4 shows an exploded illustration of the reaction plates of theapparatus according to FIGS. 1 to 3;

FIG. 5 shows a section along the line V--V in FIG. 4;

FIG. 6 shows a section along the line VI--VI in FIG. 4 and

FIG. 7 shows a detail view of a modified form of embodiment of theinvention in the region of the plate displacement part of pin form, withoverload safety device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus according to the invention, designated by 10 in theFigures, serves for the simultaneous execution of several chemicalreaction sequences. The use of the apparatus is especially preferred inthe field of biochemical reaction chains, especially the simultaneoussynthesis of several DNA lengths, even of different structures. Theapparatus 10 comprises a stack 12 of reaction plates 14 lying againstone another, which are arranged vertically one above another in theexample of embodiment as illustrated. In principle however anotherstacking direction, for example in a horizontal plane, is alsoconceivable. A plate 14 is allocated to each reaction chain (DNAlength).

For the execution of the desired reaction the plate in each case isprovided with a series of passages 16, one of which is formed with awidening serving as reaction chamber 18, as shown by FIGS. 4 and 5. Thereaction chamber 18 can be filled with abutment bodies 20, for examplein the form of small glass spheres (in English "beads") and a sieveplate 22 at the lower end and preferably also at the upper end of thereaction chamber 18 preclude escape of the abutment bodies from thereaction chamber 18.

On the plate upper side 24 in each case there are O-ring seals in theform of O-rings 26, which are inserted into ring grooves 28. These ringgrooves 28 serve for sealing the passages 16 radially outwards when theplate upper side 24 is in abutment on the plate under side 25 of thenext succeeding plate. The ring grooves 28 therefore encircle thepassages 16 concentrically with slight spacing; one of the ring grooveshas a larger diameter, namely the ring groove serving for the sealing ofthe reaction chamber 18, since the reaction chamber 18 merges upwardsinto a widening 30 which opens into the plate upper side 24.

Accordingly an attachment plate 32 downwardly adjoining the plate stack12 is provided on its upper side with O-ring seals (O-ring 34 in FIG.6), which serve for the sealing each of one of a total of six passages36. While the passages 16 extend vertically, the channels 36 are angledoff in order to render possible a horizontal connection of drainconduits 38. In FIG. 6 there may be seen a conduit connection piece 40screwed horizontally into the attachment plate 32.

To the lower attachment plate 32 there corresponds an upper attachmentplate 42, again with six horizontal attachment pieces 40 to which sixangled-off passages are connected with outlet openings 44, indicated inchain lines in FIG. 4, on the plate under side. Both attachment parts 32and 42 are provided, in the middle of their length on the verticallongitudinal side 46 lying opposite to the attachment pieces 40, with avertically extending groove 48, into which a lower and an upperengagement projection 50 and 52 respectively of pin form can penetrate.These projections 50 and 52 are fixedly fitted on a verticallydisplaceable head 54 of a plate displacement device 56 (see FIGS. 2 and3). Regarding the passages 16 and 36 it is also to be added that theseare arranged at equal distance and in the same width position each on aline on the plates 14, 32 and 42, so that in the case of appropriatemutual orientation of the plates 32, 14 and 42 the passages can bebrought into mutual alignment. On a displacement of the one or the otherplate 14 in relation to the other plates in the plate longitudinaldirection A by a distance a, which corresponds to the axial interval ofmutually immediately successive passages 16, then by reason of thisuniform passage pattern again an aligned arrangement of a part of thepassages of the plate just displaced with passages of the plates 14, 32and 42, upwardly and downwardly following this plate, takes place.

The plates 32 and 42 are provided with passages 36, according to thenumber of the different reaction fluids. In the present example fourconnections are needed for the four bases A, G, C and T. A furtherchannel serves for the feed of auxiliary fluids, as for example washingfluid. In FIG. 4 accordingly feed arrows are entered with A, C, G, T andW. An outer channel (arrow 0) can remain uncharged and then defines aparking position for the reaction chambers 18 of the plates 14. Thereresult n connections in all (n=6) with correspondingly six attachmentparts 40 in the plate 42 and in the plate 32. If necessary still furtherattachments can also be provided.

In contrast thereto the plates 14 are provided each with a total of mpassages 16 (m=2n-1=11), while the middle passage is widened to thepassage chamber 18. The reaction chamber 18 in each case can accordinglybe brought into alignment according to choice with any one of the sixconnections of the plates 32 and 42, while one of the other passages 16is also always in alignment with all the other connections. Accordinglyappropriate fluid can always be fed through the six attachment parts 40of the upper plate 42, conducted through the passages 16 of the plates14 of the plate stack 12 to the lower plate 32 and drained away throughthe lower attachment parts 40.

The reaction chamber 18 of any desired plate 14 can be brought intocontact according to choice with one of the fluids A, C, G, T or W, orinto a parking position in alignment with the attachment placed farthestleft in FIG. 4 (attachment part 40f).

In FIG. 1 the supply leads to the plate 42 and thedischarge leads 38 areomitted, likewise a pertinent valve block with reserve bottles. In FIG.2 on the other hand the valve block is represented diagrammatically anddesignated by 51. Furthermore there is seen a reserve bottle 53 of thefive reserve bottles at least. The fluid flow from the reserve bottle 53into the valve block 51 and further into the upper plate 42, thenthrough the plate stack 12 down to the lower plate 32, is indicated by adot-and-dash line 55. Then the fluid is either returned or fed to acollecting vessel.

The valve block 51 can also be formed with a directional control valve2/1, where a first fluid is fed to the one of the two entries and asecond fluid is fed to the other of the two entries. Now according tochoice either only the one or only the other or a mixture of both fluidwith pre-determined mixture ratio can be supplied through the oneoutlet, and in the latter case the valve is switched over at short timeintervals (after the style of a flip-flop element). The mixture ratio isthen defined by the ratio of the times of sojourn of the valve in thetwo control positions. This directional control valve 2/1 can naturallyalso be realised by two simple change-over valves which open into acommon outlet conduit and are opened alternately, so that either the oneor the other fluid is fed to the common outlet conduit.

In order to obtain the desired fluid pressure, so that the fluids flowthrough the stack 12, in the usual way a pressure charging of thebottles 53 with pressure gas can take place. It is also possible forfluid pumps, such for example as quantity-regulating syringes, to beused for exact volume addition.

The plate displacement device 46 includes the already mentioned head 54,which is movable to and fro in the vertical direction B' with the aid ofa drive (not represented further) with drive motor 60 arranged at thetop. The head 54 again carries a horizontal drive system (notillustrated further) with lateral drive motor 62 for the optionalhorizontal displacement (arrow D' in FIG. 1) of a plate displacementpart 64 of pin form. In FIG. 2 a dovetail guide 66 is indicated betweenherd 54 and a guide part 70 carrying the plate displacement part 64 anddisplaceable to and fro in relation to the head 54 by means of athreaded spindle 68. In the region of the plate displacement part 64 thehead 54, which encloses the part 70 in housing manner, is provided witha passage slot 71. The plate displacement part 64 protrudes in thehorizontal direction from the slot 71 and thus extends parallel with andat the equal vertical distance from the two engagement projections 50and 52 of pin form. The distance between the plate displacement part 64of pin form and the engagement projections 50 and 52 corresponds in eachcase to the thickness b of the plates 14, 32 and 42, so that when theplate displacement part 64 stands opposite to a plate 14, the twoengagement projections 50 and 52 lie opposite to the next succeedinglower and upper plates 14 and/or 32 and/or 42.

The two engagement projections 50 and 52 of pin form serve for themomentary fixing of the plates 14 on both sides of the plate 14 to bemomentarily displaced by the plate displacement part 64 of pin form, inorder to bring the reaction chamber 18 of this plate into the current ofanother of the available fluids or into the parking position.

For this purpose all the plates 14 are provided with grooves 72corresponding to the grooves 48. Since each plate 14, as alreadyexplained, can assume a total of six displacement positions in thepattern of the hole intervals a, accordingly each plate 14 is formedwith a total of six of these grooves 42 with mutual groove interval a.In each of the six displacement positions one of these grooves 72 is inalignment with the two grooves 48 of the lower and upper plates 32 and42. If all the plates 14 are situated in one of their displacementpositions, then the head 54 can be driven upwards or downwards withouthindrance, the two free ends of the engagement projections 50 and 52 ofpin form being moved upwards or downwards within this total grooveformed by the mutually aligned grooves 48, 72.

For the displacement of one of the plates 14 the head 54 is driven intothe corresponding height position, so that the plate displacement part64 of pin form lies opposite to the desired plate 14. The two engagementelements 50 and 52 then engage in blocking manner in the groove 72 ofthe two plates on both sides of the plate to be displaced. For themovement of this plate the plate displacement part is brought with itsfree end, serving as shift projection 76, to abut laterally on acounter-projection 78 of pin form, which protrudes horizontally from theopposite plate 14. Then the desired lateral displacement of the plate 14by once or more times the distance a takes place.

In order that the same plate 14 may also be shifted in the oppositedirection, the displacement projection 76, in an intermediate positionof the head 54 at the level of the surface of contact of successiveplates, is moved past the counter-projection 76, above or below it. Thenthe head 54 drives into the desired height position, so that then thedisplacement projection 78 can shift the counter-projection 76 in thedesired counter-direction.

So that the displacement projection 76 can be moved in the horizontaldirection through between the counter-projections 78 of successiveplates (in the said intermediate position of the head 54), the pindiameter of the counter-projections 78 and of the displacementprojection 76 is smaller than half the plate thickness b.

In order, after plate displacement has taken place, in the subsequentcharging of the six through-passing channels to ensure a satisfactorysealing of these channels to the exterior, that is an adequate sealingby the O-rings 26, 34 of the O-ring seals between all plates 14, 32 and42), these plates are clamped together in the stacking direction(vertical direction B') with the aid of a two-armed lever 80. Thistwo-armed lever is mounted rotatably by means of a bearing shaft 82 ontwo forward columns 84 with horizontal pivot axis 86. The two columns 84form a forward guide for the plates 14 with abutment of the plate fronts46 on the columns 84. Rear columns 88 accordingly lie against the platebacks 90. In order to obtain a high initial stress force in the case ofrelatively slight actuation force, the arm 91 of the two-armed lever 80pressing upon the plate stack is made with substantially shortereffective length than the other arm 92 to be actuated by the head 54.

For the precise lever adjustment and thus also for the setting of thedesired initial stress force, the arm 80 is formed with a kind of doublewedge. One part 94 is displaceable along a wedge face 96 of the arm 92and fixable in the desired position. A hemispherical part 97 secured tothe head 54 strikes upon the wedge 94, as soon as the head 54 isdisplaced upwards beyond the first plate displacement position. In theuppermost plate displacement position the shift projections 76 lies atthe same level as the counter-projection 78 of the uppermost plate 14.In this position the upper engagement projection 52 is situated in thegroove of the plate 42. In the subsequent movement of the head 54further upwards into an upper end position (indicated in FIG. 2 with adot-and-dash line and designated by 54'), the upper engagementprojection 52 penetrates into a groove 98, arranged accordingly invertical alignment, of a pressure application part 100 resting on theplate 42. At the same time the pressure application part 100 movesslightly downwards, under the action of the two-armed lever 80, so thatthe plate stack 12 is correspondingly compressed. The vertical groovelength of the groove 98 is accordingly large.

After reaction has taken place, for the subsequent plate displacementthe head 54 is driven downwards again, so that the two-armed lever 80becomes free and the plates 14 again lie loosely one upon another. Thusthey can again be displaced laterally.

In the arrangement according to FIG. 3 the first plate 14a ismomentarily shifted into its position placed furthest to the right(arrow D'), so that then its reaction chamber is penetrated in the nextsucceeding reaction by a fluid with the base A. The next following plate14b is in the parking position; the next following plate 14c is again inthe position allocated to the base A; the next following plates 14c to14g are in the parking position, as also the plate i. The plates 14h and14j are situated in the position allocated to the base A.

Regarding the mounting of the two-armed lever 80 it should also bementioned that alternatively it is also possible to mount this rotatablyon a head plate 110, penetrated by four columns 84 and 88, in the regionof the upper column ends; a bearing bracket engaging in the double-armedlever 80 and rigidly secured to the plate 110 is indicated in FIG. 3with a dotted outline and designated by 112. As may further be seen fromFIG. 1, the plate 110 can be made fast in each case by way of a keyholeconnection 114 on the upper ends of the columns 84, 88.

For the retention of the stack 12 at working level in front of theheight adjustment device 56, the columns 84, 88 can be of steppedformation with lower sections 115, 116 of enlarged diameter. On thestepped annular face at the upper ends of the sections 115, 116 thererests a support plate 118, on to which again the plate stack 12 is set.

When the clamping device (two-armed lever 80) is released, the plates 14can readily be shifted laterally in the manner as described, since theweight of the plate stack, with the number as illustrated, is not yetexcessively high (plates 14, especially of synthetic plastics material).The O-rings 26, 34 protruding slightly beyond the upper side 24 of theplate in each case in the relaxed condition prevent the plates from"sucking fast" to one another. In extreme cases or even in the case of ahigher number of plates, under some circumstances blocking of theparticular plate to be shifted can nonetheless occur. In order toprevent damage to the apparatus in this case, according to FIG. 7 anoverload safety device 120 can be provided. This is formed by the platedisplacement part 164 of pin form, which is made electrically conductiveand is pressed by a spiral initial stress spring 122 against a concaveseating 124 of an insulating part 126. The insulating part 126 isrigidly secured to the head 154. The insulating part 126 stands awayfrom a contact plate 128 of circular disc form. The shank of the platedisplacement part 126 of pin form between the two thickened ends isguided for displacement and to a certain degree tiltably in a guideopening 130 of a housing 132 protruding from the head 154, and there isan electrically conductive connection between the shank 134 and thehousing 132 for the one part by way of the marginal contact of the shank134 in the guide opening 130 and for the other part by way of the spring122 supported both on the electrically conductive housing 132 all roundthe opening 130 and also on the inner thickened end of the part 164. Thehousing 132 is electrically insulated from the head 154 through aninsulating plate 136. The contact plate 128 is secured within thehousing 132 with spacing therefrom on the insulating plate 136, andaccordingly electrically insulated from the housing 132. If now acorrespondingly great torque is exerted upon the free end of the platedisplacement part 164 in the displacement of the part 170 carrying thehousing 132 (corresponding to the part 70 in FIG. 2) in the directionD', then the inner end of the plate displacement part 164 slides fromthe seating 124 and is then pressed by the spring 122 against thecontact plate 128. If now the contact plate 128 and the housing 132 areparts of a current circuit, this hitherto open circuit will now beclosed by the plate displacement part 122. This can be used forswitching off the motor 62. In FIG. 7 there is seen a control system,represented as block 140, for the motor 62 which is conductivelyconnected through a connection lead 142 with the housing 132 and througha connection lead 144 with the contact plate 128. In the case ofoverload, to which reference has been made, the control system ensuresswitching off of the motor 62.

By reason of the rotationally symmetrical arrangement of contact plate122, conical insulating part 126, plate displacement part 122 andhousing 132, closure of the current circuit results even when the platedisplacement part 164 is overloaded in another direction, for examplewhen, in a vertical movement of the head 40, the plate displacement part164 strikes against any obstacle, for example one of thecounter-projections 78 of pin form. The control system 140 consequentlyswitches off both motors 60 and 62.

We claim:
 1. Apparatus for performing chemical reactions, comprising:astack (12) of reaction plates arranged one above another in a stackingdirection, said plates being movable relative to one another in astepwise manner for a constant-stepping interval (a) in a movingdirection perpendicular to said stacking direction, each of said platesbeing provided with passages arranged at mutual distances according tothe stepping interval (a), one of said passages of each of said platesbeing enlarged to form a reaction chamber; a plate moving means (56) forthe stepwise movement of any one of said plates in said movingdirection, said plate moving means including a movable head arrangedalong side said stack (12) and means for moving said head in saidstacking direction from plate to plate between two first end positions,in one of said first end positions the head confronts an outermost plateat one end of said stack, and in the other of said first end positionsthe head confronts an outermost plate of another end of said stack, saidplate moving means further including a plate moving part (64) mounted onsaid head (54) and provided for mutual engagement with and stepwisemovement of a respective one of said plates of the stack, which isconfronted by the head in said moving direction and means for movingsaid plate moving part stepwise in said moving direction; and a stackclamping means for applying a compression force parallel to saidstacking direction onto said stack in order to sealingly clamp saidplates of said stack together, said stack clamping means including apressing part (100) movable between a compression position and a releaseposition, in said compression position the pressing part (100) urgesagainst one end of the stack with said compression force, and in saidrelease position the pressing part (100) does not urge said one end ofsaid of said stack so as to allow stepping movement of said plate (16)in said moving direction, said head (54) being movable beyond one ofsaid first end positions into a second end position, and said clampingmeans further including a force transmission device coupled between saidhead (54) and said pressing part (100) so that upon movement of saidhead from said one of said first end positions into said second endposition, said pressing part is moved automatically from said releaseposition into said compression position, and vice versa.
 2. Apparatusaccording to claim 1, wherein the force transmission device comprises atwo-armed level (80) of which one end co-operates with the head (54) andanother end co-operates with the pressing part (100).
 3. Apparatusaccording to claim 2, wherein at least one of the ends of the two-armedlevel (80) is provided with a clamping pressure adjusting device. 4.Apparatus according to claim 3, wherein the clamping pressure adjustingdevice is formed by an adjustable double wedge (94).
 5. Apparatusaccording to claim 2, wherein the head (54) of the plate moving means(56) is provided on its upper side with a projection (97) which, on amovement of the head (54) beyond said one of said first end positionsinto said second end position acts on the one end of the two-armed level(80).
 6. Apparatus according to claim 1, wherein O-ring seals (26, 34)between successive plates (14) are provided for sealing the passages(16) to the exterior.
 7. Apparatus according to claim 1 wherein liquidis fed to the passages (16) of the stack (12) by way of a mixer valvearrangement (51).
 8. Apparatus according to claim 1, wherein each ofsaid plates is elongated and has an axis of elongation parallel to theaxis of elongation of the other plates and normal to said stackingdirection.
 9. Apparatus for performing chemical reactions, comprising:astack (12) of reaction plates arranged one above another in a stackingdirection, said plates being movable relative to one another in astepwise manner for a constant stepping interval (a) in a movingdirection perpendicular to said stacking direction, each of said platesbeing provided with passages arranged at mutual distances according tothe stepping interval (a), one of said passages of each of said platesbeing enlarged to form a reaction chamber; a plate moving means (56) forthe stepwise movement of any one of said plates in said movingdirection, said plate moving means including a movable head arrangedalong side said stack (12) and means for moving said head in saidstacking direction from plate to plate between two first end positions,in one of said first end positions the head confronts an outermost plateat one end of said stack, and in the other of said first end positionsthe head confronts an outermost plate of another end of said stack, saidplate moving means further including a plate moving part (64) movablymounted on said head (54) and provided for mutual engagement with andstepwise movement of a respective one of said plates of the stack, whichis confronted by the head in said moving direction, means for movingsaid plate moving part stepwise in said moving direction; and a stackclamping means for applying a compression force parallel to saidstacking direction onto said stack in order to sealingly clamp saidplates of said stack together, said stack clamping means including apressing part (100) movable between a compression position and a releaseposition, in said compression position the pressing part (100) urgesagainst one end of the stack with said compression force, and in saidrelease position the pressing part (100) does not urge said one end ofsaid of said stack so as to allow stepping movement of said plate (16)in said moving direction, a shift lock means being provided which,during movement of one of said plates by said plate moving part (64)locks one of the neighboring plates of said moving plates againstmovement in said moving direction, said shift lock means being mountedon said head (54).
 10. Apparatus according to claim 9, wherein the shiftlock means is constructed so as to lock simultaneously both neighboringplates of said moving plate.
 11. Apparatus according to claim 10,wherein said shift lock means includes tow engagement elements (52)rigidly mounted on the head (54) so as to engaged with acounter-engagement element provided on each of said both neighboringplates (14).
 12. Apparatus according to claim 11, wherein one of theengagement element and counter-engagement element comprises anengagement projection (50, 52), the other of the elements comprises aplurality of engagement grooves (72) arranged one after another in themoving direction at the stepping interval, extending parallel to thestacking direction and constructed for the receipt of the engagementprojection.
 13. Apparatus according to claim 11, wherein one of theengagement element and counter-engagement element comprises anengagement groove extending parallel with the stacking direction, theother of the elements comprises a plurality of engagement projectionsarranged one after another in the moving direction at the steppinginterval (a) and constructed for insertion into any one of said grooves.14. Apparatus according to claim 12, wherein a pressure application part(100) provided at one end of said stack is formed with an additionalengagement groove (98) constructed for the receipt of the engagementprojection (52).
 15. Apparatus according to claim 9, wherein each ofsaid plates is elongated and has an axis of elongation parallel to theaxis of elongation of the other plates and normal to said stackingdirection.
 16. Apparatus for performing chemical reactions, comprising:astack (12) of reaction plates arranged one above another in a stackingdirection, said plates being movable relative to one another in astepwise manner for a constant stepping interval (a) in a movingdirection perpendicular to said stacking direction, each of said platesbeing provided with passages arranged at mutual distances according tothe stepping interval (a), one of said passages of each of said platesbeing enlarged to form a reaction chamber; a plate moving means (56) forthe stepwise movement of any one of said plates in said movingdirection, said plate moving means including a movable head arrangedalong side said stack (12) and means for moving said head in saidstacking direction from plate to plate between two first end positions,in one of said first end positions the head confronts an outermost plateat one end of said stack, and in the other of said first end positionsthe head confronts an outermost plate of another end of said stack, saidplate moving means further including a plate moving part (64) movablymounted on said head (54) and provided for mutual engagement with andstepwise movement of a respective one of plates of the stack, which isconfronted by the head in said moving direction and means for platemoving said plate moving part stepwise in said moving direction; and astack clamping means for applying a compression force parallel to saidstacking direction onto said stack in order to sealingly clamp saidplates of said stack together, said stack clamping means including apressing part (100) movable between a compression position and a releaseposition, in said compression position the pressing part (100) urgesagainst one end of the stack with said compression force, and in saidrelease position the pressing part (100) does not urge said one end ofsaid of said stack so as to allow stepping movement of said plate (16)in said moving direction, the plate moving part including a projection(76) mounted onto a carrier part (170), said carrier part (170) beingmovable in said moving direction relative to said head by said platemoving part moving means of said plate moving means, said projection(76) cooperating selectivity with a counter projection (78) formed oneach of said plates (14).
 17. Apparatus according to claim 16, whereinthe moving projection (76), in an intermediate position of the head (54)between successive plate moving positions of said head, is movablefreely between the counter-projections (78) of successive plates (14).18. Apparatus according to claim 16, wherein at least one of the movingprojection (76) and the counter-projections (78) is of pin form. 19.Apparatus according to claim 16, wherein the plate moving part (164)includes an overload safety means for preventing damage to said platesmoving part when engaging a respective one of said plates.
 20. Apparatusaccording to claim 19, wherein the plate moving part (164) is anelectrically conductive pin and is movable between a normal position andan overload position, and wherein a spring element (122) is provided,said spring element (122) urging said moving part (164) against anisolating part (126) in said normal position of said moving part (164)and against an electrically conductive control plate (128) in saidoverload position of said plate moving part (164).
 21. Apparatusaccording to claim 16, wherein each of said plates is elongated and hasan axis of elongation parallel to the axis of elongation of the otherplates and normal to said stacking direction.